Background of the Invention
1. Field of the Invention
[0001] This invention relates to flywheels and is particularly directed to ultralight shell
construction for flywheels and methods of forming the same.
2. Description of the Prior Art
[0002] Traditionally, flywheels have been massive devices which have relied upon their mass
to store energy. For example, the flywheels of automobile engines typically weigh
about 50 to 100 pounds and rotate at several hundred rpm. More recently, it has been
recognized that the equation which defines the amount of energy stored by a flywheel
is equal to the mass times the square of the velocity. In accordance with this, attempts
have been made to increase the energy stored in flywheels by increasing the speed
of rotation of the flywheel. Unfortunately, this also increases the centrifugal forces
which tend to cause the flywheel to fly apart with explosive results. Consequently,
current flywheel research has been directed toward designing low-weight, high-velocity
flywheels. Thus, modern flywheels are designed for rotational speeds of 10,000-20,000
rpm. However, no flywheel structures have been proposed heretofore which are capable
of withstanding prolonged rotation at these speeds. Consequently, the search for improved
flywheel structures has continued.
Brief Summary and Objects of the Invention
[0003] The disadvantages of the prior art are overcome with the present invention and a
flywheel construction is proposed which is extremely light in weight and economical
to produce, yet is extremely strong and resistant to centrifugal focus at high rates
of revolution. In addition, a method of producing the flywheel construction is provided.
[0004] The advantages of the present invention are preferably attained by providing a flywheel
construction having a small diameter hub and a removable mandrel extending radially
outward from the hub. A first plurality of high-strength fibers, impregnated with
a suitable binder, are wrapped circumferentially about the mandrel and a second plurality
of binder-impregnated, high-strength fibers are wrapped about the mandrel and the
first plurality of fibers in directions tangential to the hub to form an outer shell
for the flywheel. Thereafter, the mandrel is removed to form a hollow, light-weight
flywheel.
[0005] Accordingly, it is an object of the present invention to provide an improved flywheel.
[0006] Another object of the present invention is to provide a light-weight flywheel which
is strong enough to withstand prolonged rotation at high speeds, together with a method
of forming the flywheel.
[0007] A specific object of the present invention is to provide a light-weight flywheel
comprising a hub, a first plurality of high-strength fibers impregnated with a binder
and wrapped circumferentially about the hub but spaced radially from said hub, and
a second plurality of binder impregnated fibers wrapped tangentially about said hub
and extending about the first plurality of fibers to form an outer shell for said
flywheel, together with a method for forming the flywheel by providing a removable
mandrel about the hub, wrapping the first and second plurality of fibers about the
mandrel, and removing the mandrel to provide a hollow, light-weight flywheel.
[0008] These and other objects and features of the present invention will be apparent from
the following detailed description, taken with reference to the figures of the accompanying
drawing.
Brief Description of the Drawings
[0009]
Fig. 1 is a vertical section through a flywheel embodying the present invention;
Fig. 2 is a view, similar to Fig. 1, showing the mandrel in place during formation
of the flywheel; and
Fig. 3 is a plan view of the flywheel of Fig. 1 with a portion of the shell broken
away for clarity.
Detailed Description of the Preferred Embodiment
[0010] In that form of the present invention chosen for purposes of illustration, Fig. 1
shows a flywheel, indicated generally at 2, having a hub 4 of relatively small radial
dimension. A removable mandrel 6 is mounted on the hub 4 and extends radially outward
therefrom. A first plurality of high-strength fibers impregnated with a suitable binder
material, such as a resin, are wound circumferentially about the mandrel 6, as seen
at 8 in Fig. 1, and a second plurality of binder-impregnated, high-strength fibers
are wound about the periphery of the mandrel 6 and first plurality of fibers 8 in
directions tangential to the hub 4, as seen at 10.
[0011] After the binder material of the second plurality of fibers 10 has set, the mandrel
6 is removed to provide a hollow, light-weight flywheel construction of extremely
high strength. The mandrel 6 may be inflatable for mounting on the hub 4 to enable
winding of the fibers 8 and 10 thereabout and may subsequently be deflated for removal.
Alternatively, the mandrel 6 may be formed of rigid material which can be removed
by melting, dissolution or disassembly after the fibers 8 and 10 have been wound thereon.
[0012] Obviously, numerous variations and modifications can be made without departing from
the present invention. Accordingly, it should be clearly understood that the form
of the present invention described above and shown in the accompanying drawing is
illustrative only and is not intended to limit the scope of the invention.
[0013] What is claimed and desired to be secured by Letters Patent of the United States
is:
1. A flywheel comprising:
a hub having a relatively small diameter;
a first plurality of resin-impregnated fibers extending circumferentially about said
hub with the innermost portion of said first plurality of fibers spaced a substantial
distance radially from said hub; and
a second plurality of resin-impregnated fibers extending tangentially with respect
to said hub and enclosing said first plurality of fibers and the space between said
first plurality of fibers and said hub to form a shell for said flywheel.
2. The flywheel of Claim 1 further comprising a mandrel filling the space between
said hub and said first plurality of fibers during assembly of said flywheel and removable
upon completion of such assembly.
3. The method of assembling a flywheel, said method comprising the steps of:
mounting a removable mandrel about the hub of said flywheel;
winding a first plurality of resin-impregnated fibers about said mandrel circumferentially
with respect to said hub;
winding a second plurality of resin-impregnated fibers tangentially about said hub
to enclose said mandrel and said first plurality of fibers; and
removing said mandrel.
4. The flywheel of Claim 2 wherein said flywheel is inflatable for winding said fibers
and deflatable for removal.
5. The flywheel of Claim 2 wherein said mandrel is formed of rigid material which
can be melted for removal.
6. The flywheel of Claim 2 wherein said mandrel is formed of rigid material which
can be dissolved for removal.
7. The flywheel of Claim 2 wherein said mandrel is formed to provide a rigid structure
during assembly of said flywheel and which can be disassembled for removal.
8. The method of Claim 3 wherein said removing step comprises deflating said mandrel.
9. The method of Claim 3 wherein said removing step comprises dissolving said mandrel.
10. The method of Claim 3 wherein said removing step comprises melting said mandrel.